A polarization separation device has a grating having a recurring blaze-shaped grating pattern formed on one surface of a transparent base plate and an optically anisotropic material layer arranged adjacent to the grating and having different refractive indices in the direction in which the grating pattern recurs and in the direction perpendicular to that direction. The polarization separation device separates light incident thereon into two linearly polarized light components that have polarization planes perpendicular to each other in accordance with the polarization directions thereof by refracting one and simply transmitting the other of those two linearly polarized light components. Here, the refractive index N0 of the grating and the refractive indices Ne and Np of the optically anisotropic material layer with respect to one and the other, respectively, of the linearly polarized light components are defined as follows: EQU .vertline.Ne-N0.vertline..gtoreq.0.2, and EQU .vertline.Np-N0.vertline..ltoreq.0.03.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A polarization separation device comprising: a grating having a recurring blaze-shaped grating pattern formed on one surface of a transparent base plate; and an optically anisotropic material layer arranged adjacent to the grating and having different refractive indices in a direction in which the grating pattern recurs and in a direction perpendicular to that direction, wherein the polarization separation device separates light incident thereon into two linearly polarized light components that have polarization planes perpendicular to each other in accordance with polarization directions thereof by refracting one and simply transmitting the other of those two linearly polarized light components, wherein the following conditions are fulfilled: EQU .vertline.Ne-N0.vertline..gtoreq.0.2, and EQU .vertline.Np-N0.vertline..ltoreq.0.03, where N0 represents a refractive index of the grating, Ne represents the refractive index of the optically anisotropic material layer with respect to one of the linearly polarized light components, and Np represents the refractive index of the optically anisotropic material layer with respect to the other of the linearly polarized light components.
2. A polarization separation device as claimed in claim 1, wherein the optically anisotropic material layer is made of nematic liquid crystal.
3. A polarization separation device as claimed in claim 1, wherein the following condition is fulfilled: EQU 0.1.ltoreq..vertline.Ne-Np.vertline..ltoreq.0.3 where Ne represents the refractive index of the optically anisotropic material layer with respect to one of the linearly polarized light components, and Np represents the refractive index of the optically anisotropic material layer with respect to the other of the linearly polarized light components.
4. A polarization separation device as claimed in claim 1, wherein the grating pattern recurs at intervals of 5 to 1.5 .mu.m.
5. A polarization separation device comprising: a grating having a recurring blaze-shaped grating pattern formed on one surface of a transparent base plate; an optically anisotropic material layer arranged adjacent to the grating and having different refractive indices in a direction in which the grating pattern recurs and in a direction perpendicular to that direction; and a lens array layer having a plurality of lens surfaces and arranged on an entrance side or exit side of the polarization separation device, wherein the polarization separation device separates light incident thereon into two linearly polarized light components that have polarization planes perpendicular to each other in accordance with polarization directions thereof by refracting one and simply transmitting the other of those two linearly polarized light components.
6. A polarization separation device as claimed in claim 5, wherein the lens array layer is formed on the transparent base plate and on an entrance side of the optically anisotropic material layer.
7. A polarization separation device as claimed in claim 5, wherein the optically anisotropic material layer is made of nematic liquid crystal.
8. A polarization separation device as claimed in claim 5, wherein the following conditions are fulfilled: EQU .vertline.Ne-N0.vertline..gtoreq.0.2, and EQU .vertline.Np-N0.vertline..ltoreq.0.03, where N0 represents a refractive index of the grating, Ne represents the refractive index of the optically anisotropic material layer with respect to one of the linearly polarized light components, and Np represents the refractive index of the optically anisotropic material layer with respect to the other of the linearly polarized light components.
9. A polarization separation device as claimed in claim 5, wherein the following condition is fulfilled: EQU 0.1<.vertline.Ne-Np.vertline..ltoreq.0.3, where Ne represents the refractive index of the optically anisotropic material layer with respect to one of the linearly polarized light components, and Np represents the refractive index of the optically anisotropic material layer with respect to the other of the linearly polarized light components.
10. A polarization separation device as claimed in claim 5, wherein the grating pattern recurs at intervals of 5 to 1.5 .mu.m.
11. A polarization separation device comprising: a grating having a recurring blaze-shaped grating pattern formed on one surface of a transparent base plate; and an optically anisotropic material layer arranged adjacent to the grating and having different refractive indices in a direction in which the grating pattern recurs and in a direction perpendicular to that direction, wherein the polarization separation device separates light incident thereon into two linearly polarized light components that have polarization planes perpendicular to each other in accordance with polarization directions thereof by refracting one and simply transmitting the other of those two linearly polarized light components, wherein the grating has minute grooves formed on a surface thereof facing the optically anisotropic material layer along one of the two directions.
12. A polarization separation device as claimed in claim 11, wherein the minute grooves are grinding streaks formed in a metal mold with which the grating is molded.
13. A polarization separation device as claimed in claim 11, wherein the optically anisotropic material layer is made of nematic liquid crystal.
14. A polarization separation device as claimed in claim 11, wherein the following conditions are fulfilled: EQU .vertline.Ne-N0.vertline..gtoreq.0.2, and EQU .vertline.Np-N0.vertline..ltoreq.0.03, where N0 represents a refractive index of the grating, Ne represents the refractive index of the optically anisotropic material layer with respect to one of the linearly polarized light components, and Np represents the refractive index of the optically anisotropic material layer with respect to the other of the linearly polarized light components.
15. A polarization separation device as claimed in claim 11, wherein the following condition is fulfilled: EQU 0.1.ltoreq..vertline.Ne-Np.vertline..ltoreq.0.3 where Ne represents the refractive index of the optically anisotropic material layer with respect to one of the linearly polarized light components, and Np represents the refractive index of the optically anisotropic material layer with respect to the other of the linearly polarized light components.
16. A polarization separation device as claimed in claim 11, wherein the grating pattern recurs at intervals of 5 to 1.5 .mu.m.
17. A projection-type display apparatus comprising: a polarization separation device for separating light incident thereon into two linearly polarized light components that have polarization planes perpendicular to each other in accordance with polarization directions thereof by refracting one and simply transmitting the other of those two linearly polarized light components, comprising: a grating having a recurring blaze-shaped grating pattern formed on one surface of a transparent base plate; and an optically anisotropic material layer arranged adjacent to the grating and having different refractive indices in a direction in which the grating pattern recurs and in a direction perpendicular to that direction; a light source for emitting light; a light condenser for condensing the light emitted from the light source so as to form it into a substantially parallel beam; a first lens array having a plurality of lenses; a second lens array having a plurality of lenses arranged one for each of the lenses of the first lens array in such a way that the two linearly polarized light components exiting from the polarization separation device are made to converge on two different lenses of the second lens array; a polarization plane rotator for rotating the polarization plane of one of the linearly polarized light components having passed through the second lens array so as to make it identical with the polarization plane of the other of the linearly polarized light components having passed through the second lens array; a spatial light modulation device for modulating light having passed through the second lens array so as to form an optical image; and a projection optical system for projecting the optical image, wherein the following conditions are fulfilled: EQU .vertline.Ne-N0.vertline..gtoreq.0.2, and EQU .vertline.Np-N0.vertline..ltoreq.0.03, where N0 represents a refractive index of the grating, Ne represents the refractive index of the optically anisotropic material layer with respect to one of the linearly polarized light components, and Np represents the refractive index of the optically anisotropic material layer with respect to the other of the linearly polarized light components.
18. A projection-type display apparatus comprising: a polarization separation device for separating light incident thereon into two linearly polarized light components that have polarization planes perpendicular to each other in accordance with polarization directions thereof by refracting one and simply transmitting the other of those two linearly polarized light components, comprising: a grating having a recurring blaze-shaped grating pattern formed on one surface of a transparent base plate; an optically anisotropic material layer arranged adjacent to the grating and having different refractive indices in a direction in which the grating pattern recurs and in a direction perpendicular to that direction; and a lens array layer having a plurality of lens surfaces and arranged on an entrance side or exit side of the polarization separation device; a light source for emitting light; a light condenser for condensing the light emitted from the light source so as to form it into a substantially parallel beam; a first lens array having a plurality of lenses; a second lens array having a plurality of lenses arranged one for each of the lenses of the first lens array in such a way that the two linearly polarized light components exiting from the polarization separation device are made to converge on two different lenses of the second lens array; a polarization plane rotator for rotating the polarization plane of one of the linearly polarized light components having passed through the second lens array so as to make it identical with the polarization plane of the other of the linearly polarized light components having passed through the second lens array; a spatial light modulation device for modulating light having passed through the second lens array so as to form an optical image; and a projection optical system for projecting the optical image.
19. A projection-type display apparatus comprising: a polarization separation device for separating light incident thereon into two linearly polarized light components that have polarization planes perpendicular to each other in accordance with polarization directions thereof by refracting one and simply transmitting the other of those two linearly polarized light components, comprising: a grating having a recurring blaze-shaped grating pattern formed on one surface of a transparent base plate; and an optically anisotropic material layer arranged adjacent to the grating and having different refractive indices in a direction in which the grating pattern recurs and in a direction perpendicular to that direction, wherein the grating has minute grooves formed on a surface thereof facing the optically anisotropic material layer along one of the two directions; a light source for emitting light; a light condenser for condensing the light emitted from the light source so as to form it into a substantially parallel beam; a first lens array having a plurality of lenses; a second lens array having a plurality of lenses arranged one for each of the lenses of the first lens array in such a way that the two linearly polarized light components exiting from the polarization separation device are made to converge on two different lenses of the second lens array; a polarization plane rotator for rotating the polarization plane of one of the linearly polarized light components having passed through the second lens array so as to make it identical with the polarization plane of the other of the linearly polarized light components having passed through the second lens array; a spatial light modulation device for modulating light having passed through the second lens array so as to form an optical image; and a projection optical system for projecting the optical image.
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May 3, 2000
August 21, 2001
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